A frequency synthesizer is an important part of the wireless transceiver. The frequency synthesizer provides a local oscillation signal for the transceiver, performance of the frequency synthesizer directly determines performance level of the transceiver system, and power consumption of the frequency synthesizer often occupies a large proportion of overall power consumption of the transceiver. In recent years, with increasing development of wireless communication technology, more and more transceivers have developed to multi-mode and multi-standard, and many broadband and multi-band single-terminal transceiver chips which satisfy various kinds of communication standards are emerging. As a critical component of the transceiver, the frequency synthesizer in this kind of transceiver system needs to provide a very wide frequency range of local oscillation signal, and there are different locking times, phase noise performances etc. as required in different communication standards. If a plurality of frequency synthesizers are used for achieving the different locking times, phase noise performances etc., the system will often be complicated, and the cost will be difficult to control. In order to reduce the cost and improve integration level, it is desired that a single frequency synthesizer may satisfy requirements of various communication standards for the local oscillation signal; and also, if the performance (including the locking time, power consumption level, phase noise etc.) of the frequency synthesizer can implement reconstruction, the application of the frequency synthesizer will become more flexible.